Under certain circumstances an automobile or other vehicle cannot be started when a battery lacks a sufficient charge to provide the necessary current to start an engine in the automobile. Such a situation is more likely to exist under cold weather conditions. When the battery charge is inadequate it is necessary to "jump start" the automobile from a charged power source. Frequently, a battery in a second automobile fills the need of a charged power source.
Battery jumper cables have been used to couple the discharged battery to the charged battery. The jumper cables typically consist of a pair of conductors with a pair of battery clamps at either end. Each battery has a positive or plus terminal and a negative or minus terminal, representing the relative voltage levels at the two terminals. With such an arrangement it is necessary to use the jumper cables to couple the plus terminals of each battery together, as well as the minus terminals of each battery together, in a parallel configuration.
Depending upon the position and condition of the battery in the automobile it is not always easy to see terminal identification markings on the battery. Furthermore, in cold weather conditions it is desirable to spend a minimum amount of time in connecting the jumper cables to the respective batteries. Yates, U.S. Pat. No. 4,400,658, describes jumper cables which can be utilized without regard to which is the plus or the minus terminal on each battery. However, the Yates patent requires the use of non-standard and obsolete components in its construction.
An additional problem with prior art jumper cables is the danger which exists when jump starting a vehicle having a battery which is frozen or completely discharged. An excessive current, such as in a starting condition, through a completely discharged battery may cause the battery to errupt. Similarly, when a battery is frozen a large current causes a build-up of hydrogen gas and heat in the battery. If warping of plates inside the battery occurs there may be sparking, causing the gas to ignite, thereby exploding the battery.
The present invention is intended to overcome these and other problems with battery jumper cables.